vrocrider

1991Toy RV. 65K miles. Engine stock with EGR. Sat for last 6 years with half tank & Stabil. Prior to park had new ignition components fuel filter and ran fine from Atlanta to Texas. Has had head gasket replacement under recall.

The story. New battery. Started after a few tries to my surprise. Ran rough and had the smell of old gas. Extreme pinging. Drained gas tank, new fuel filter. Not much change. No CEL. CEL does work. Drove to Alabama with several bottles of Techron along the way. Only able to reach 45 - 50 MPH on highway. No improvement during drive. Terrible pinging. Engine rocks so bad it cracked lower radiator hose neck.

Checked for cracks in air tube from MAS to throttle body. Checked for cracked vacuum lines. Checked plugs. All a brownish gold on insulator. Checked cap & rotor button. Checked fuel pressure. Good at idle. Cleaned throttle body. Installed 6 rebuilt Bosch 4 holes fuel injectors. Noticed that 3 of the intake plenum were much cleaner than the other 3. Not sure why. Jumpered CEL terminals. Continuous flashing so I assume that means no codes. Pulled small filters out of each pulled injector & they all were clean.

Result, slight improvement but still same issues. Noticed animal nest under plenum & a little wire insulation damage from critters. Timing seems right as it cranks right up. Engine a little rough at idle. Still pinging & hesitant to get up to speed.

Next step...initially leaned toward a fuel issue but now thinking more ignition. Based on reading forums about engine ping plan to replace distributor. Will buy a timing light and verify timing. One mechanic suggested I test for fuel pressure at speed where fuel regulator kicks in.

Suggestions?

Thanks for any assistance.

scope103

Sounds like you've spent a lot of money to avoid buying a $20 timing light. You should start there. Read the manual; you need to jumper TE1 to E1 to get it to base timing.

The fuel pressure regulator "runs" all the time, like any fuel-injected engine. Testing fuel pressure is a good idea, but requires a gauge and the fitting to plumb into the fuel system. An easier method that is almost as useful is to pull the fuel return from the FPR, and replace with a clear vinyl hose to a suitable container. Jumper FP to B+ to force the fuel pump to run with key-on, and you should get about 1/2 liter/min out of the fuel return. If the flow is less than that, you might not have enough flow into the rail to hold the pressure up when the engine is sucking fuel. Which points to the fuel filter (among others).